ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 119 
is washed in water, dried in the air, and mounted in balsam, styrax, or 
dammar. 
The grana or microsomes were best brought out by staining with 
some anilin dye and then differentiating with 2 per cent, acetic acid. 
Spores are very easily stained by treating the preparation with 
boiling phenolfuchsin aud then washing out in 4 percent, sulphuric acid. 
The yeasts used for these observations were natural cultivations of 
ordinary bottom yeasts. The yeast was shaken up with distilled water 
and then, after settling, the fluid decanted off. The sediment, after 
having been thus treated several times, was kept for the observations. 
Method for Discovering Tubercle Bacilli in Milk with the Centri- 
fuge.* — Herr Ilkewitsch says that he has successfully employed the 
following method for detecting tubercle bacilli in milk after these 
organisms had been precipitated by the centrifuge. The author was 
led to this procedure by finding that the intraperitoneal inoculation 
of guinea-pigs and rabbits was ofttimes unsuccessful. After the cream 
has been separated 20 ccm. of the milk are coagulated with citric acid. 
The residue separated from the whey by filtration is dissolved in an 
aqueous solution of sodic phosphate, treated with 6 ccm. of sulphuric 
ether, and then shaken up for 10 to 15 minutes. 
The solution below the fat layer is drawn off by opening a tap at the 
bottom of the collecting vessel and then placed in the centrifuge. The 
sediment is separated from the fluid by means of a copper ball dropped 
into the separation-tube. This allows the fluid to be poured off and the 
sediment left behind. The sediment is then spread out on cover-glasses 
and obtained in the usual way. 
(4) Staining- and Injecting. 
Method for Staining Tubercle Bacilli.-)*— Dr. B. A. van Ketel has 
devised the following procedure for detecting tubercle bacilli in sputum, 
&c. In a wide-mouthed flask capable of holding about 100 ccm., 
10 ccm. of water and 6 ccm. of acid, carbolic, liquefactum are mixed. 
About 10-15 ccm. of the fluid to be examined are then added and the 
flask having been closed with a caoutchouc stopper is vigorously 
shaken for about a minute. With milk or very thin sputum the water 
may be omitted. After the shaking the fluid becomes milky ; the flask is 
then filled up with water and again shaken. The fluid is then poured 
into a conical glass and allowed to subside. In from 12 to 24 hours 
some of the deepest lying sediment is removed with a pipette and spread 
on a cover-glass. The dried and heated cover-glass preparation is then 
washed in ether or chloroform and afterwards in alcohol, or the pre- 
paration may be treated with ether-alcohol. This is specially necessary 
if the preparation turn out rather thick. The cover-glass is then 
stained by the Ziehl-Neelsen method. The foregoing procedure is 
extremely simple, easily carried out, and produces a bright distinct 
microscopical picture. 
* Miinchen. Med. Wochenschr., 1892, No. 5. See Centralbl. f. Bakteriol. u. 
Parasitenk., xii. (1892) pp. 441-2. 
f Aich. f. Hygiene, xv. pp. 109-24. See Centralbl. f. Bakteriol. u. Parasitenk., 
xii. (1892) pp. 689-90. 
